Many modern electronic systems require integrated current drive systems for providing current to drive peripheral systems such as solenoids, speakers, lamps, etc. A peripheral systems such as a solenoid usually utilizes a large drive transistor which may be, for example, a large bipolar transistor. According to known methods, these drive transistors are usually forced to operate in a range having an h.sub.fe of approximately 15-20. Accordingly, to provide an output current on the order of, for example, 1.3 amps, a base drive current of 75 milliamps is provided. Prior art methods of monitoring the base drive current involve the use of conventional emitter resistors. The processing used to construct the emitter resistor can result in variability in the value of the resistance of up to 50 percent. Due to this variability, prior art systems had to set the current 50 percent higher to insure that adequate current was output by the circuit to drive the peripherals. When operating with a battery supply source, it is desirable to reduce the current when it is not needed. After the solenoid plunger has seated, less current is needed to hold it seated. With the emitter resistor used to monitor the hold current, for example, if the current required was 150 milliamps, the nominal current would be set at on the order of 225 milliamps. Due to the variability inherent in the emitter resistor, the actual current could go well over 300 milliamps resulting in a great deal of unnecessary power dissipation across the hold transistor.
Accordingly, a need has arisen for a circuit which can accurately set the output current provided to peripheral systems by a current driver circuit such that an exact required current can be provided without the need for excess current and resulting power dissipation.